New Mexico Sen. Martin Heinrich during a hearing on Capitol Hill. AP Photo/J. Scott Applewhite Sen. Martin Heinrich aggressively questioned Attorney General Jeff Sessions on Tuesday over his decision not to share details of his conversations with President Donald Trump.

During a highly-anticipated Senate Intelligence Committee hearing, the New Mexico Democrat confronted Sessions about his refusal to reveal non-classified conversations with the president after Sessions dodged a question about whether Trump expressed dissatisfaction over Sessions' recusal from the investigation into Russia's interference in the 2016 election.

"My understanding is that you took an oath, you raised your right hand today and said you would solemnly swear to tell the truth, the whole truth, and nothing but the truth. And now you're not answering questions," Heinrich said. "You're impeding this investigation."

He continued:

"So my understanding of the legal standard is either you answer the question, that's the best outcome. You say 'This is classified, can't answer it here, I'll answer it in closed session,' that's bucket number two. Bucket number three is to say I'm invoking executive privilege. There is not appropriateness bucket. That is not a legal standard. Can you tell me what are these long-standing DOJ rules that protect conversations made with the executive without invoking executive privilege?"

The attorney general said it was a "longstanding policy of the Department of Justice" not to reveal conversations between the attorney general and the president, saying he would need to share the questions with the president.

"Can you share those policies with us?" Heinrich asked. "Are they written down at the Department of Justice?"

"I believe they are," Sessions replied.

"This is the appropriateness legal standard for not answering congressional inquiries?" Heinrich asked.

Sessions replied, "It's my judgment that it would be inappropriate for me to reveal conversations with the president when he has not had a full opportunity to review the questions and to make a decision and approve such an answer."

Heinrich then noted that there were two ongoing investigations into Russian interference in the 2016 election.

"You are obstructing that congressional investigation by not answering these questions," Heinrich said. "And I think your silence, like the silence of [Director of National Intelligence Dan Coates], like the silence of [NSA Director Mike Rogers], speaks volumes."

Some Republicans were not pleased with Heinrich's line of questioning.

Minutes later, Sen. James Lankford took a swipe at the New Mexico senator, saying that former Attorney General Eric Holder would not discuss some conversations between himself and then-President Barack Obama.

"It seems to be a short memory about some of the statements that Eric Holder would and would not make to any committee in the House and the Senate," Lankford said.

Other Democrats continued to question Sessions over his refusal to answer questions about his conversations with Trump, despite being under oath.

Sen. Jack Reed asked Sessions to provide the written rules he cited, while Sen. Kamala Harris asked whether Sessions himself reviewed the policy before relying on it to refuse to answer questions.